Domestic appliance



y 1943- F. H. M coRMxcK 2,320,041

DOMESTIC APPLIANCE Filed July 5, 1940 4 Sheets-Sheet 1 May 1943. F. H. MCORMICK 2,320,041

DOMESTIC APPLIANCE Filed July 5, 1940 4 Sheets-Sheet 2 May 25, 1943. F.H. MCCORMICK DOMESTIC APFLIANCE Filed July 5* 1940 4 Sheets-Sheet 3z/z/alNvENTOR. 2

M y 1943- F. H. MCCORMICK 2,320,041

DOMESTIC APPLIANCE Filed July 5, 1940 4 Sheets-Sheet 4 V C/GR M Z C ZEPatented May 25, 1943 I UNITED STATES PATENT OFFICE DOMESTIC APPLIANCEFrancis H. McCormick, Dayton, Ohio, assignor to General MotorsCorporation, Dayton, Ohio, a corporation of Delaware Application July 5,1940, Serial'No. 344,018

IGIaim.

This invention relates to a domestic appliance and more particularly tosurface heaters for electric ranges.

It is an object of my invention to provide a surface heater of thetubular sheath type in.-

which the upper surface of the sheath is held rig.

. idly in a single plane.

It is another object of my invention to provide an arrangement for asurface heater of the tubular sheath type whereby the heater can bereadily cleaned without disturbing the electrical connections.

It is another object of my invention to provide connections. Theterminal blocks are so formed an arrangement of a surface heater of thetubuiar sheath type in which the terminal connections are adequatelyshielded from spillage.

It is another object of my invention to provide a terminal member for asurface heater in which the terminal connections are so located as to beprotected from spillage.

It is still another object of my invention to provide a surface heaterof the tubular sheath type in which the sheath is very small in diameterso that it may be more readily formed into the desired configuration inorder to obtain the desired heat distribution.

It is another object of my invention to provide a two-element surfaceheater of the tubular sheath type having an improved configuration toprovide improved heat distribution.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had'to the accompanyingdrawings, wherein a preferred form of the present invention is clearlyshown.

In the drawings:

Fig. 1 is a top view of one of the surface heaters of an electric rangeincluding its terminal block;

Fig. 2 is a sectional view taken along the line 2-2 of Fig. 1;

Fig. 3 is a sectional view taken along the line 3-4 of Fig. 1;

Fig. 4 is a sectional view taken along the line 4l of Fig. 3;

Fig. 5 is a sectional view showing the method of lifting up one of thesurface heaters for clean- 8 P p Fig. 6 is an exposed view of theterminal block and connections;

Fig. 'l is a sectional view of the terminal block taken along the line'l-'I of Fig. 2;

Fig. 8 is a sectional view taken along the line H of Fig. 2;

that the connections from thesurface heating units and from. the switchmechanism enter upon the bottom sides of the block so that the entrancesare protected from spillage from above as shown in Fig. 2.

I have shown an electric range in which the surface heaters are of thetubular sheath type. The surface heaters are of the two-element type forgeneral operation with a. three-wire Edison circuit with the innerelement operating at maximum wattage when connected to a 115 voltcircult and the outer element operating at maximum wattage whenconnected to a 230 volt circult. The two elements of each unit arewelded to a framework and surrounded by a ring in order to insurerigidity. The ends of each of the connections extend downwardly andthence are curved outwardly to terminate in their respective terminalblocks which are located beneath the top surface of the electric rangewhere they are shielded from spillage.

Referring now to the drawings and more particularly to Fig. 1 there isshown a surface heating unit 26 supported in the flanged aperture of thesupporting top 22 of an electric range. This heating unit includes aninner element 60 and an outer element 62.

The inner element 60 begins with a looped end 64 and extends in aclockwise direction around a central disk 66 t0 the extent of nearly 360after which it extends radially outwardly as indicated by the referencecharacter 68, thence downwardly to form a portion indicated by thereference character 10 followed by a lower portion 12 which is curvedoutwardly and upwardly so that its two end enter the terminal block 14upon its face 18. This face 16 is turned slightly downwardly so thatliquid cannot drain into the interior of the terminal block through theapertures provided for the sheathed elements. The outer element 82begins with the looped end 18 which i adjacent the radially extendingportion 68 and ex-- tends in a counter-clockwise direction around theinner element 60 until it again reaches the radially extending portion68, after which'it extends of high chrome-nickel steel.

terminal block II through-tho face 25., downwardly and outwardly ex dingportions of both elements are all Each. of the elements contains ahelical electrical conductor such as the conductors l4 and 05. Theseconductors are each surrounded by a suitable electrical insulatingmaterial, such as magnesium oxide designated by the reference character55, and the insulating material is enclosed within a tubular metalsheath. preferably The sheath of the inner element is designated by thereference character 55 and the sheath of the outer element by 52. Theelements may be made by any suitable process, for example, one similarto that shown in the Lightioot Patent 1,359,400 may be used for itsmanufacture. After the elements assaosi The 1 wardly Projecting lip illwhich together with a lower projection I ll firmly locks the ends of thechannels to the projecting portions of the rim Ill. The lowerproiections III 'are bent outwardly as shown in dotted lines in Fig.9 inorder to allow the projection I" to be placed in the notch III. Afterthis the proiections I are bent straight again so' that the projectionsIII are firmly locked in place within notches III.

'Ihe rim III is madefrom a straight strip of metal and i curled intocircular form with its Joint adjacent the terminal 14. This joint ismade rigid by the connecting piece II I which is welded to the two endsof the strip forming the rim so as to make a flrm Joint which ispractically invisible. This connecting piece III also serves are bent tothe shape shown in Fig. 1 they are slightly flattened upon their uppersurface as shown in Figs. 1 and 2, thus providing a greater contact areawith the kitchen utensils used.

These elements are rigidly supported upon a framework formedby thecrossed stainless steel channel members 04 and 55 which are eachprovided with a narrow bead 55 for contact welding the members to thebottoms of theelements as hereafter explained. These channels arenotched at their centers to provide an overlapping Joint beneath theornamental disk 55 which is fastened to another disk 55 which in turn isspotwelded to the channel members 54 and 55 in order to reinforce theiroverlapping joint to flrmly hold the channel members together.

The elements and 52 are preferably fastened to the crossed channels 54and .55 by contact or to locate the surface heaters radially. since itis provided with a tongue adapted to register with the notch II2provided in the flange III surrounding the aperture provided in thesupporting surface 22 of the range. The rim I55 is provided with aflange .III which rests upon the flange III of the supporting top 22. Bythis construction the upper suri'acesof each element are maintainedrigidly in a single plane.

Beneath each heating unit is a metal reflector- III which may be formedof aluminum coated steel, chrome plated metal or stainless steel inorder to reflect the radiant energy from the heating elements forinsulating purposes; This reflector I I9 reflects any heat rays from theheatprojection welding. This step is illustrated in, I

Fig. 10 which shows a portion of the inner element III together with aportion of one of the channels 55. As shown, the crossed channel membersare supported upon a lower supporting member I52 which is shaped so thatit supports 1 the channel members directly beneath'the'narrow bead 55which is provided for welding Ipurposes. The two elements are'thenplacedupon the crossed channel members in proper .position after which a'pivoted weighted member illflisbrought to bear upon the uppersurface.or-the' elements and 52 in order to hold themfirmly upon the variousportions'of thegbeadlfl. [The i lower supporting member I52 is connectedbya suitable conductor'I55 to thefsecondar'y'coil ill of a transformer.The primary coil" III of the transformer is connected/tea power sourceunder the control of a; manual switch .152. The

other end of thesecondiau y"coil;I55. is connected by a conductor I toapivote'dsupporting arm I55 for'the weighted members.I". When 1 the;

ing element upwardly onto the bottom surface of the container beingusedupon the surface heater. The reflector Ii! is provided with the flangeI2I which rests upon the flange II5 beneath the rim I55. The reflectorH5 is provided with the drain aperture I25 beneath the central disk 55so as to catch and drain any spillage which may fall between theconvolutions of the heating elements from the containers used on top ofthe rang'e. The spillage will pass through the flanged aperture I23 ontoa drain pan normally provided beneath the reflector. The reflector I I!isprovided with a cut-out or cut-away portion I25 through which thedownwardly extendingportions Iii and 55 ofthe inner and outer heatingelements pass.

,1: shouldbe noted that the terminal block is is not beneath the heatingunit but is beneath the supporting top 22 of the range so that anyliquid f-which spills upon the heating unit will not fail upontheterinihal block and possibly'enter to ca'usefa short circuit. Also bycurving the terminal outwardly infthe manner described the entireassembled heating element-may be lifted upswitch I52 is closed:currentjpasses' through'the secondary circuit and sufli'cient currentto weld wardly asshown in .Fig. 5 without disturbing the electricalconnections to the switch mechanism. This exposes the reflector II!which may also be lifted and entirely removed for more convenient:cleaning if desired, without further disturbance.

passes between the elementsand the, channels I at the crossing pointsbetween the beads and the various portions of the elements. ThisDiOV'ides portion of the heating unit. ill-call this, projec tionwelding;

The opposite ends a simple method for. simultaneously welding'theelements to the channels at-the-crossing points I as the conductorterminal of'the channel members are I provided withnotches similar tothe notch IlI- in Fig.3. Each ofthese notches 'IOI receives the adjacentstruck-in portion III of the rim Ill Within the sheathing of each vicalelectrical resistors are connected at their ends to a solid electricalconductor terminal such I3I.- This conductor Ill protrudesv from the endof the sheathing which is cut of! to expose the end of the solidconductor-terminal Iii. The end of the sheathing is fitted into a metalcap is: which is fastened to the terminal block I4 by the screws I 25which are threaded into'the bushing I21. The terminal block- 14 ismolded of some suitable electrical insulating plastic as shown in Fig. cwith the threaded bushing I2Ijlodged directly in the'recess element, thehe1-.

I29. The conductor I3I within the terminal block 14 issecurely fastenedto a rectangular terminal lug I31.

When the cap I33 is fastened in place upon the terminal block 14, theterminal lugs I31 extend into the recesses I39. The threaded aperture MIin each of the terminal lugs I31 then registers with the center of oneof the round passages I43 extending to the face I45 of the terminalblock 14. A cup washer I41 fits into each of the recesses I43 and one ofthe binding screws I49 receives the eyeletted end of one of the flexibleconductors I50 extending from the switch mechanism. Each of thesebinding screws extend through the aperture in one of the cup washers I41and is threaded into one of the terminal lugs I31 in order to providethe necessary electrical connection between the particular flexibleconductor extending from the/switch mechanism and the conductor terminalI3I which connects to the helical conductor within the sheathing. Whenin operating position, the face 16 as well as the face I45 of theterminal block 14 are each turned partially downwardly so that liquidfalling upon the terminal block in its normal position will not enterthe passages provided for the difierent conductors but these passageswill be protected by the impervious upper faces of the block.

This two-part heating unit is connected to a three-wire Edison circuitthrough a multi-heat switch mechanism to secure various other lowerwattage inputs with resulting changes in heat distribution for variouscooking purposes. Several of the circuits which apply are disclosed inmy copending application S. N. 236,471, filed ctober 22, 1938.

In Fig. 9 I have shown a heating unit which is larger in size than theunit shown in Figs. 1 to 5, but which is identical in other respectsexcepting that the outer element 222 is provided with a loop 226 withinthe inner elements 224. Like the smaller unit 26 the larger unit issupported within the flanged aperture of the range top 226 which coversthe terminal block 228. The unit is provided with a rim 230 which restsupon the flange of the aperture in the range top 226. This rim isprovided with struck-in portions 232 which support the ends of thecrossed stainless steel channel members 234 which are each provided witha narrow welding bead 236 upon which rests the bottoms of the twoelements at the points at which they cross the channel members 234. Thechannel members 234 are provided with a orntral disk 238 as in thesmaller unit. The elements 222 and 224 are fastened to the crossedchannel members by projection welding as in the smaller unit. The endportions of the elements extend downwardly and are curved outwardly sothat they extend into one of the downwardly turned faces of the terminalblock 228 exactly in the manner as shown best in Figs. 2 and 5 inconnection with the smaller unit.

The provision of the additional inner loop 226 '6: the outer element 222greatly improves the heat distribution of the larger unit by providingheat in the center as well as the edge portions by the outer element andin particular makes it possible to make the outer element much longerthan the inner element. This lends itself admirably to my preferredarrangement of operating the inner element at a maximum wattage uponvolts and the outer element at maximum wattage upon 230 volts instandard three-wire Edison circuit.

As mentioned in connection with the smaller unit, the elements of thelarger unit are connected by flexible electric conductors to a multiheatswitch mechanism which in turn is connected to a three-wire Edisoncircuit source in order to secure various lower wattage inputs withresulting changes. Several of the circuits which apply are disclosed inmy co-pending application S. N. 236,471, filed October 22, 1938.

While the form of embodiment ofthe invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claim whichfollows.

What is claimed is as follows:

A multi-element surface heater of the tubular sheath type including atubular double loop sheath element extending in a substantially circularfashion for nearly 360, a second tubular sheath element having a, singlesubstantially circular loop portion within and in the same plane as thefirst element, said second element having a double loop second portionextending in a sub-' stantially circular fashion outside of and in thesame plane as the first element.

FRANCIS H. MCCORMICK.

